They don’t co mingle though. They segregate themselves into “Mexican neighborhoods”, “Indian neighborhoods”, etc. They marry and socialize amongst themselves.
Ignoring the inherent racism in your repeated use of "they", the second generation absolutely joins the "melting pot". Say what you will about Texas, I'm not sure I've ever encountered more mixed race/mixed culture couples than I did during a week spent in Houston. And I've lived in at least four different major US metros in my lifetime.
And what is your contribution to addressing that? It is easy to call entire groups of people "they", but they are people to and maybe the rest of society needs to welcome them with an open heart before they'll integrate.
I think you're overestimating how sensitive immigrants are to this stuff. Comarriage is way more about preserving their family culture than it is about finding someone accepting. Religion and spoken-at-home language will matter.
Sizeable chunks of some immigrant populations simply won't melt, which IMO is fine in a place like Canada or the US. They'll still work with everyone else, and I feel like profession and class are both way bigger dividers than ethnicity anyway. A white SWE probably knows more Indian SWEs than white janitors.
Religion is somewhat a concern, but it's completely dwarfed by issues around the religiosity of non-immigrant populations.
Speaking a different language at home is a really good thing. Kids are going to pick up English through immersion anyway, so they're going to turn out bi/multilingual. That's great.
So, most of my extended family is from the Middle East, mostly Christian with some Muslim in-laws. My understanding is that those immigrant groups are far more religious and traditional than the average non-immigrant (though less than the extreme parts), which of course I'm fine with cause they're my own. But I'm not sure what you're expecting from them.
I'm not expecting anything from them! Just pointing out that the actual problem with religion in, say, the US, is white Christian nationalism, with fundamentalist Islam a distant second.